Earthquake-the shaking of the Earth's crust Stress-force that changes a rock's shape or volume Shearing-stress that pushes a mass of rock in opposite directions Tension-stress that stretches rock so that it becomes thinner in the middle Compression-stress that squeezes rock until it folds or breaks Deformation-a change in volume or shape of Earth's crust Fault-a break in Earth's crust where slabs of rocks slip past each other Strike-slip fault-a type of fault where rocks either side move past each other sideways with little up-or-down motion Normal fault-a type of fault where the hanging wall slides downward Reverse fault-type of fault where the hanging wall slides upward Hangingwall- block of rock that forms the upper half of a fault Footwall-block of rock that forms the lower half of the fault Fault-blockmountain-mountain that forms where a normal fault uplifts a block of rock Fold-bend in rock that forms when Earth's crust is compressed Anticline-an upward fold in rock Syncline-a downward fold in rock Plateau-a land form that has a more or less level surface and is elevated high above sea level
Outline:
Stress in the Crust
stress adds energy to rocks
movements of Earth's plates creates powerful forces that squeezes or pulls the rock in the crust
energy is stored in the rock until the rock either breaks or changes its shape
Types of Stress
three types
shearing
cause rock to break and slip apart or to change its shape
tension
effect on rock is like pulling apart a piece of warm bubble-gum
compression
squeezes rock until it folds or breaks
most changes in the crust occur so slowly that they cannot be observed directly
Kinds of Faults
faults usually occur along plate boundaries, where the forces of plate motion compress, pull or shear the crust so much that the crust breaks
strike-flip faults
created by shearing
forms transform boundaries between two plates
example-San Andreas Fault, California
normal faults
caused by tension
forms at an angle
half of the fault that lies above is the hanging wall
half of the fault that lies below is the footwall
when movement occurs, hanging wall slips downward
example: Rio Grande Rift Valley, New Mexico
reverse faults
caused by compression forces
hanging wall slides up and over the footwall
example: Appalachian Mountains
Friction along Faults
force that opposes the motion of one surface as it moves across another surface is referred to as Friction
how rocks move along a fault depends on how much friction there is between the opposite sides of the fault
Mountain Building
over millions of years fault movement can change a flat plain into a towering mountain range.
mountains formed by faulting
when normal faults uplifts a block of rock, fault-block mountain is created
Example of Fault block mountain range-Sierra Nevada
mountains formed by folding
the collisions of two plates can cause compression and folding of the crust
largest mountain range-Himalayas (Asia) and The Alps (Europe)
folding rocks can fracture and produce faults
anticlines and Synclines
example of anticline: Black Hills of South Dakota
example of Syncline: Illinois Basin
plateaus
force that raise mountains can also raise plateaus
Table of Contents
2.1 Earth's Crust in Motion
Vocabulary
Earthquake-the shaking of the Earth's crust
Stress-force that changes a rock's shape or volume
Shearing-stress that pushes a mass of rock in opposite directions
Tension-stress that stretches rock so that it becomes thinner in the middle
Compression-stress that squeezes rock until it folds or breaks
Deformation-a change in volume or shape of Earth's crust
Fault-a break in Earth's crust where slabs of rocks slip past each other
Strike-slip fault-a type of fault where rocks either side move past each other sideways with little up-or-down motion
Normal fault-a type of fault where the hanging wall slides downward
Reverse fault-type of fault where the hanging wall slides upward
Hanging wall- block of rock that forms the upper half of a fault
Footwall-block of rock that forms the lower half of the fault
Fault-block mountain-mountain that forms where a normal fault uplifts a block of rock
Fold-bend in rock that forms when Earth's crust is compressed
Anticline-an upward fold in rock
Syncline-a downward fold in rock
Plateau-a land form that has a more or less level surface and is elevated high above sea level
Outline:
Stress in the Crust
Types of Stress
Kinds of Faults
Friction along Faults
Mountain Building
Diagram